Conveyor system with conveyor carriage running on rails

ABSTRACT

A conveyor carriage has running wheels guided in rail parts so as to prevent the conveyor carriage from lifting off transversely to the plane of the rails. Each conveyor carriage contains a driving unit with at least one driving wheel prestressed against the rail. In order to move the conveyor carriage manually, a lifting device allows the driving wheel to be lifted off and disengaged from the rail. In order to simplify the lifting device, the lifting device is equipped with a shaft mounted on the conveyor carriage adjoined to the driving unit by a flexible coupling member.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase of PCT/EP96/02058 filed May 14,1996 and based, in turn, in national application 1567/95-0 inSwitzerland, filed May 26, 1995 under the International Convention.

FIELD OF THE INVENTION

The invention relates to a conveyor system. More particularly, theinvention relates to a conveyor system of the type in which a conveyorcarriage has running wheels riding on rails and the carriage cannot belifted transversely off the rails and wherein at least one driving wheelon the carriage is prestressed against one of the rails.

BACKGROUND OF THE INVENTION

Several conveyor systems of the above mentioned type are known, forexample from U.S. Pat. No. 3,636,883. With such conveyor carriages thatcannot be lifted off from the rails, that the driving wheel is active atall times. Depending on the type of gear mechanism, the resistance in adriving wheel can range from infinity in the case of a self-lockinggear, to nearly zero in the case where no transmission gear is presentbetween the motor and the driving wheel. Accordingly, depending on theconstruction of the gear mechanism, the driving wheel will exert avariable resistance against a manual displacement, so that movement ofthe conveyor carriages within the rails may be either impossible ordifficult.

OBJECT OF THE INVENTION

The aim of the invention is to provide a conveyor system of the kinddescribed hereinabove, in which the conveyor carriage can also be movedmanually if this should be necessary.

SUMMARY OF THE INVENTION

This object is achieved according to the invention by providing a devicefor lifting off the driving wheel from the rail that is accessible fromoutside and can be actuated manually. The driving wheel can thus bedisengaged and the conveyor carriage can be moved manually, which isadvantageous, e.g. in case of malfunctions, shunting manoeuvres orcorrections of the position of the conveyor carriage.

In principle, it is possible to provide the conveyor carriage with onlyone driving wheel, which can be designed as a friction wheel or as agear wheel. In many cases the conveyor carriage will contain as drivingwheels both a friction wheel and a gear wheel that are arranged next toeach other on the same shaft, such that when the gear wheel is engaged,the friction wheel is disengaged, whereas in the absence of a tooth rackthe driving action is taken over by the friction wheel.

There are several possibilities for ensuring the pre-stressing of thedriving wheel. For example, the driving unit may be disposed basicallyrigidly, with only the driving axis being movable and pre-stressedtransversely to the plane of the rails. Particularly advantageous is anembodiment wherein the driving unit is swivel-mounted on the carriageabout an axis that is parallel but spaced from an axis of the drivingwheel.

There are also various possibilities for the device for lifting off thedriving wheel from the rail. More particularly, the lifting device canhave a shaft that is rotatably mounted to the running gear of theconveyor carriage and the shaft can be connected through a couplingmember with the driving unit such that upon a swiveling of the shaft,the driving with its driving wheel is lifted off from its rail. Thecoupling member thereof can be a cam plate or a lever gear, but anembodiment wherein the coupling member is a flexible element that isconnected at one end with the driving unit and at the other end can bewound on the shaft, is particularly advantageous.

It is particularly advantageous if the lifting device is designed insuch a way that it is lockable in the lift-off position of the drivingwheel, so that the lifting device needs not be continuously actuateduntil the displacement process has been completed. However, the lockingshould not occur in every case but only in a second phase of thedisplacement of the lifting device, whereas in a first phase the liftingdevice should have to be constantly held manually in order to ensurethat upon release of the lifting device the automatic engaging of thedriving device on to the rail is guaranteed. An advantageousconstruction of the locking device provides that the shaft will have abasic position in which it is prestressed by means of a spring with astep against an abutment. The shaft is further guided in a bore and hasat least one radial ledge that engages in a radial recess in the wall ofthe bore. The bore has a further radial recess corresponding to thelocking position in which the radial ledge engages after swivelingoutside of the bore.

Particularly advantageous is a further embodiment of the conveyorsystem, which prevents the driving wheel from lifting offunintentionally from the rail.

In this further embodiment the shaft is provided with a locking camwhich, in a basic position of the shaft, abuts against an abutment ofthe driving unit so as to prevent it from swiveling.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 is an elevational view which shows the running gear of a conveyorcarriage hanging in a rail, in section along line I--I of FIG. 2;

FIG. 2 is a sectional view which shows the conveyor system of FIG. 1, insection along line II--II of FIG. 1;

FIG. 3 is a view similar to FIG. 1 which shows the conveyor system ofFIG. 1 with the driving wheel lifted off; and

FIG. 4 is a detail view which shows the mounting of a lifting shaft, insection along IV--IV of FIG. 2.

SPECIFIC DESCRIPTION

The parts of the conveyor system represented in detail in the figuresshow the running gear 2 of a conveyor carriage 4 in a rail 6. Theconveyor carriage includes running wheels 8 and a driving wheel 12driven by a driving unit 10, which driving wheel in the instant caseincludes a friction wheel 12a and a gear wheel 12b. The conveyorcarriage 4 runs in a rail 6 that prevents the conveyor carriage fromlifting off transversely to the rail plane. For example, the railincludes a rail base 14 and lateral rail parts 16 that engage runningwheels 8 in a C-shape, so that the conveyor carriage 4 cannot be removedperpendicularly from the rails.

The driving unit 10 is swivel-mounted on frame 22 of running gear 2around an axis 20 that is parallel to axis 18 of the driving wheel 12. Abiasing spring 24 pre-stresses driving wheel 12 against the rail base14, so that either friction wheel 12a is engaged with a friction surface26 of the rail base 14 or, like in the example shown, gear wheel 12b isengaged with a tooth rack 28 at the rail base 14.

The conveyor carriage 4 is provided with an externally manually actuateddevice 30 for lifting the driving wheel 12, 12a or 12b, respectively,from rail 6. This lifting device 30 includes a shaft 32 disposedparallel to the drive axis, which shaft is rotatably and axially movablymounted in running gear 2. The shaft is provided with a handle 34 thatpermits swivelling of shaft 32 as well as axial movement of shaft 32, aswill be described in more detail hereinbelow. Shaft 32 is provided witha locking cam 36 that in its basic position S0 according to FIG. 1 abutsagainst an abutment 38 of the driving unit 10, so as to preventswivelling of the latter. Furthermore, shaft 32 is connected withdriving unit 10 by means of a coupling member 40, said coupling member40 consisting of a flexible element, such as a rope, belt or ribbon, oneend 42 of which is attached to the driving unit 10 and the other end 43of which is attached to shaft 32. Upon swivelling of shaft 32, couplingmember 40 is wound up on the shaft, while at the same time locking cam36 is disengaged from abutment 38 and coupling member 40 is wound up onshaft 32. Thereby, driving unit 10 is swivelled against the force ofbiasing spring 24 until driving wheel 12 is disengaged from rail 16.

The lifting device 30 is provided with locking device 44, which locksthe lifting device in the basic position S0 shown in FIG. 1, in order toprevent unintentional swivelling of shaft 32. For this purpose, shaft 32is provided with a step 46, so that by means of a biasing spring 48shaft 32 is brought into contact through step 46 against a wall 50 thatis located on the side remote from handle 34. In wall 50 there isincluded a bore 52 that includes two diametrically opposite radialrecesses 54, into each of which a radial ledge 56 of shaft 32 engagesand thereby secures the shaft against swivelling. Shaft 32 can bedisplaced in axial direction 58 by means of handle 34 until the shaft isin contact with the outer part of wall 50 by means of a securing ring60, whereby radial ledges 56 are disengaged from radial recesses 54 andthe shaft can be swivelled, as can be deduced from FIG. 1. Position S0is the basic position in which driving wheel 12 is engaged with railbase 14. Upon swivelling by about 30° into the first position S1,locking cam 36 is released. Upon further swivelling by 90° into positionS2, gear wheel 12b is disengaged from tooth rack 28, so that theconveyor carriage can be moved along rail 6. In this position, handle 34has to be held in place manually, otherwise biasing spring 24 would moveback driving unit 10 into the basic position. only upon furtherswivelling of the handle 34 by 180° from the basic position S0 intoposition S3 can the lifting device 30 be locked, by engaging radialledges 56 into radial recesses 54. Such a locking is, however, onlyadvisable where the rail takes a horizontal course. In case of obliqueor even vertical course of the rail the locking should not be used, inorder to ensure that in the event of unintentional release of handle 34the gear wheel 12b immediately engages into tooth rack 28, thuspreventing an undesired departure of the conveyor carriage.

I claim:
 1. A conveyor system comprising a conveyor carriage running onrails, said conveyor carriage having:a running gear with running wheelsguided in parts of said rails so as to prevent the conveyor carriagefrom lifting off transversely to a plane of the rails; a driving unit onthe carriage that is pre-stressed against one of the rails andswivel-mounted about an axis parallel to but spaced from an axis of adriving wheel of the driving unit; and a lifting device carried on therunning gear for lifting off the driving wheel from said one of saidrails, said lifting device including a movable part movable between abasic position in which the driving wheel is pre-stressed against saidone of said rails, a labile lift-off position and a stable lift-offposition, said movable part having a shaft that is rotatably mounted tothe running gear of the conveyor carriage and that is provided with ahandle accessible on the outside of the running gear, the shaft beingconnected with the driving unit by a flexible coupling member that iswindable up onto the shaft.
 2. The conveyor system according to claim 1,wherein the lifting device is lockable in the stable lift-off position.3. The conveyor system according to claim 2, wherein the shaft in itsbasic position is pre-stressed by means of a spring with a step againstan abutment of the running gear, the shaft further being guided in abore and being provided with at least one radial ledge that engages in aradial recess in the wall of the bore, the bore including a furtherradial recess corresponding to a locking position, into which the radialledge engages after swivelling outside of the bore.
 4. The conveyorsystem according to claim 1 wherein the shaft is provided with a lockingcam, which in the basic position of the shaft abuts against an abutmentof the driving unit, so as to prevent it from swivelling.